The U.S. Capitol building is seen reflected in a puddle at sunrise on the day of the U.S. midterm election as voters go to the polls across the country to elect 33 U.S. senators and all 435 members of the U.S. House of Representatives in Washington, U.S., November 6, 2018. REUTERS/Jim Bourg

WASHINGTON (Reuters) - The U.S. Congress on Thursday approved a two-week stopgap spending bill to avert a government shutdown, setting up a potential showdown over President Donald Trump’s proposed border wall later this month.

Without action by Congress, funding for several federal agencies, including the Department of Agriculture, State Department and Department of Homeland Security, had been set to expire this week. The stopgap bill extends funding through Dec. 21.

Before the stopgap bill expires, the Republican-led Congress is expected to consider a $450 billion bill to fund the departments through the fiscal year that ends next Sept. 30.

Trump has demanded $5 billion this year as part of his plan to build a wall on the border with Mexico that Democrats argue would be ineffective at keeping out illegal immigrants and illicit drugs.

Instead, Democrats want to continue improving less costly fencing and employing high-tech instruments to detect illegal border crossings. They have agreed to include $1.6 billion for additional border security.

“Let me be clear: the $1.6 billion cannot be used to construct any part of President Trump’s 30-foot-tall concrete border wall. It can only be used for fencing, using technology currently deployed at the border, and only where the experts say fencing is appropriate and makes sense,” Senate Minority Leader Chuck Schumer said on Thursday.

Trump has threatened to force a partial government shutdown if Congress does not give him the money he wants for the wall.